The document DE 10 2012 201 881 A1 describes a control set-up for an electric bicycle, including an acceleration sensor for detecting somebody starting to ride.
A determination of the angle of inclination of a path of travel as a function of a detected acceleration and of a measured wheel speed is described in the document EP 1 213 561 A1.
As a rule, calculation of the speed in bicycle computers or e-bike systems, i.e., electric bicycles, requires knowledge of the wheel circumference. In the case of bicycle computers, the wheel circumference must be measured by the customer, or a literature value for the specific tire model must be found and programmed in. In the case of an electric bicycle, the wheel circumference is often permanently programmed in by the bicycle manufacturer and cannot be adjusted by the end user, since the wheel circumference has a decisive influence on the frequently statutory limiting speed of the electric bicycle. However, when changing the tire, for example, from street tires to knobby tires, the wheel circumference can change. If the wheel circumference of the e-bike system is not adjusted in accordance with the change, then inaccuracies occur in the calculation of speed, as well as in further tachometer functions. In addition, power losses of the electric bicycle can occur due to a change in the tire circumference. For example, the electric bicycle having motor assistance can no longer reach the speed attained in the condition as shipped.